/*
** The crc32 is licensed under the Apache License, Version 2.0, and a copy of the license is included in this file.
**
**Author:Wang Yaofu voipman@qq.com
**Description: The source file of class crc8.
** following parameters:
**
** Width                      : 8 bit
** Poly                       : 0x31 (That is actually x^8 + x^5 + x^4 + 1)
** Initialization             : 00
** Reflect Input byte         : False
** Reflect Output CRC         : False
** Xor constant to output CRC : 00
** Output for "123456789"     : a2
*/

#include "crc8.h"


static const uint8_t crc8tab_lsb[256] = {
        0x00, 0x04, 0x08, 0x0c, 0x10, 0x14, 0x18, 0x1c,
        0x20, 0x24, 0x28, 0x2c, 0x30, 0x34, 0x38, 0x3c,
        0x23, 0x27, 0x2b, 0x2f, 0x33, 0x37, 0x3b, 0x3f,
        0x03, 0x07, 0x0b, 0x0f, 0x13, 0x17, 0x1b, 0x1f,
        0x25, 0x21, 0x2d, 0x29, 0x35, 0x31, 0x3d, 0x39,
        0x05, 0x01, 0x0d, 0x09, 0x15, 0x11, 0x1d, 0x19,
        0x06, 0x02, 0x0e, 0x0a, 0x16, 0x12, 0x1e, 0x1a,
        0x26, 0x22, 0x2e, 0x2a, 0x36, 0x32, 0x3e, 0x3a,
        0x29, 0x2d, 0x21, 0x25, 0x39, 0x3d, 0x31, 0x35,
        0x09, 0x0d, 0x01, 0x05, 0x19, 0x1d, 0x11, 0x15,
        0x0a, 0x0e, 0x02, 0x06, 0x1a, 0x1e, 0x12, 0x16,
        0x2a, 0x2e, 0x22, 0x26, 0x3a, 0x3e, 0x32, 0x36,
        0x0c, 0x08, 0x04, 0x00, 0x1c, 0x18, 0x14, 0x10,
        0x2c, 0x28, 0x24, 0x20, 0x3c, 0x38, 0x34, 0x30,
        0x2f, 0x2b, 0x27, 0x23, 0x3f, 0x3b, 0x37, 0x33,
        0x0f, 0x0b, 0x07, 0x03, 0x1f, 0x1b, 0x17, 0x13,
        0x31, 0x35, 0x39, 0x3d, 0x21, 0x25, 0x29, 0x2d,
        0x11, 0x15, 0x19, 0x1d, 0x01, 0x05, 0x09, 0x0d,
        0x12, 0x16, 0x1a, 0x1e, 0x02, 0x06, 0x0a, 0x0e,
        0x32, 0x36, 0x3a, 0x3e, 0x22, 0x26, 0x2a, 0x2e,
        0x14, 0x10, 0x1c, 0x18, 0x04, 0x00, 0x0c, 0x08,
        0x34, 0x30, 0x3c, 0x38, 0x24, 0x20, 0x2c, 0x28,
        0x37, 0x33, 0x3f, 0x3b, 0x27, 0x23, 0x2f, 0x2b,
        0x17, 0x13, 0x1f, 0x1b, 0x07, 0x03, 0x0f, 0x0b,
        0x18, 0x1c, 0x10, 0x14, 0x08, 0x0c, 0x00, 0x04,
        0x38, 0x3c, 0x30, 0x34, 0x28, 0x2c, 0x20, 0x24,
        0x3b, 0x3f, 0x33, 0x37, 0x2b, 0x2f, 0x23, 0x27,
        0x1b, 0x1f, 0x13, 0x17, 0x0b, 0x0f, 0x03, 0x07,
        0x3d, 0x39, 0x35, 0x31, 0x2d, 0x29, 0x25, 0x21,
        0x1d, 0x19, 0x15, 0x11, 0x0d, 0x09, 0x05, 0x01,
        0x1e, 0x1a, 0x16, 0x12, 0x0e, 0x0a, 0x06, 0x02
};

static const uint8_t crc8tab_msb[256] = {
        0x00, 0x31, 0x62, 0x53, 0xc4, 0xf5, 0xa6, 0x97,
        0xb9, 0x88, 0xdb, 0xea, 0x7d, 0x4c, 0x1f, 0x2e,
        0x43, 0x72, 0x21, 0x10, 0x87, 0xb6, 0xe5, 0xd4,
        0xfa, 0xcb, 0x98, 0xa9, 0x3e, 0x0f, 0x5c, 0x6d,
        0x86, 0xb7, 0xe4, 0xd5, 0x42, 0x73, 0x20, 0x11,
        0x3f, 0x0e, 0x5d, 0x6c, 0xfb, 0xca, 0x99, 0xa8,
        0xc5, 0xf4, 0xa7, 0x96, 0x01, 0x30, 0x63, 0x52,
        0x7c, 0x4d, 0x1e, 0x2f, 0xb8, 0x89, 0xda, 0xeb,
        0x3d, 0x0c, 0x5f, 0x6e, 0xf9, 0xc8, 0x9b, 0xaa,
        0x84, 0xb5, 0xe6, 0xd7, 0x40, 0x71, 0x22, 0x13,
        0x7e, 0x4f, 0x1c, 0x2d, 0xba, 0x8b, 0xd8, 0xe9,
        0xc7, 0xf6, 0xa5, 0x94, 0x03, 0x32, 0x61, 0x50,
        0xbb, 0x8a, 0xd9, 0xe8, 0x7f, 0x4e, 0x1d, 0x2c,
        0x02, 0x33, 0x60, 0x51, 0xc6, 0xf7, 0xa4, 0x95,
        0xf8, 0xc9, 0x9a, 0xab, 0x3c, 0x0d, 0x5e, 0x6f,
        0x41, 0x70, 0x23, 0x12, 0x85, 0xb4, 0xe7, 0xd6,
        0x7a, 0x4b, 0x18, 0x29, 0xbe, 0x8f, 0xdc, 0xed,
        0xc3, 0xf2, 0xa1, 0x90, 0x07, 0x36, 0x65, 0x54,
        0x39, 0x08, 0x5b, 0x6a, 0xfd, 0xcc, 0x9f, 0xae,
        0x80, 0xb1, 0xe2, 0xd3, 0x44, 0x75, 0x26, 0x17,
        0xfc, 0xcd, 0x9e, 0xaf, 0x38, 0x09, 0x5a, 0x6b,
        0x45, 0x74, 0x27, 0x16, 0x81, 0xb0, 0xe3, 0xd2,
        0xbf, 0x8e, 0xdd, 0xec, 0x7b, 0x4a, 0x19, 0x28,
        0x06, 0x37, 0x64, 0x55, 0xc2, 0xf3, 0xa0, 0x91,
        0x47, 0x76, 0x25, 0x14, 0x83, 0xb2, 0xe1, 0xd0,
        0xfe, 0xcf, 0x9c, 0xad, 0x3a, 0x0b, 0x58, 0x69,
        0x04, 0x35, 0x66, 0x57, 0xc0, 0xf1, 0xa2, 0x93,
        0xbd, 0x8c, 0xdf, 0xee, 0x79, 0x48, 0x1b, 0x2a,
        0xc1, 0xf0, 0xa3, 0x92, 0x05, 0x34, 0x67, 0x56,
        0x78, 0x49, 0x1a, 0x2b, 0xbc, 0x8d, 0xde, 0xef,
        0x82, 0xb3, 0xe0, 0xd1, 0x46, 0x77, 0x24, 0x15,
        0x3b, 0x0a, 0x59, 0x68, 0xff, 0xce, 0x9d, 0xac
};

// LSB-first
uint8_t crc8_lsb(const char *buf, int len) {
    int counter;
    uint8_t crc = 0;
    for (counter = 0; counter < len; counter++)
        crc = crc8tab_lsb[crc ^ *buf++];
    return crc;
}

// MSB-first
uint8_t crc8_msb(const char *buf, int len) {
    int counter;
    uint8_t crc = 0;
    for (counter = 0; counter < len; counter++)
        crc = crc8tab_msb[crc ^ *buf++];
    return crc;
}
